US2407974A - Ultra high frequency device - Google Patents

Description

Sept. 24, 1946.

D. G. CLIFFORD ErAL 2,407,974

ULTRA HIGH FREQUENCY DEVICE Filled Dec. 29, 1942 ATTORNEY Patented Sept. 24, 1946 UNITED STA-TES PATENT orificeI l2,407,9rc ULTRA HIGH FRQUNGY DEVICEl David Gordon Clifford, Palo Alto, Calif., and Ilia',` E; Mouromtsei,` Montclair, N; J., assignors to Westinghouse Electric Corporation, East Pittsburgh, Pa., a corporation ofv Pennsylvania Application December'29, 1942-, Serial` No; 170;{190

4 Claims. (Cl. 2504215) This invention relates generally to ultra high fecti'vef and ecient ultra high frequency device characterized. as a cavity resonator detector.

Likewise, from a general aspect, an object of the invention is` to" overcome the difficulties enu-` merated above` and to materially improve prior arlt constructicnsA of ultra highI frequency devlic'esand especially diodes Y More specifically an object of the'l invention is to provide an ultra high frequency device aschar-` acterized wherein4 tuningi is obtained while the l electron emission and reception characteristics a few thousandths of an inch. Thus onediih- I cultyf encountered in the prior art has been to l adequately reduce the spacing and maintain an evenV spacing of so srnall an amount without a contact inadvertently" occurring and short circuit resulting.

In considering the incorporation ofaresonant cavity as an integral part of a diode as above characterized, and wherein the electrodes of the diode'Al are reentrant intoy the resonant cavitythe problem of tuning without disturbing the elec'- -trode spacing has heretofore eludedr adequate solution. The necessity of avoidingv contact of the electrodes referred to above is a more serious problem when one of the electrodes has to be moved for tuningE purposes thanwhen both are permanently* fixed. A further difticulty is ,also introduced, in that heretofore a shifting of one electrode for tuning purposes not only changed the-L capacitative relation of the' electrodes', but altered the electrodey spacingA and transit time of the electrons, whichA was highly detrimental.

When utilizing a resonant cavity for ultra high frequency oscillations, the' interior or cavity wall constitutes a conductive surface for high. frequency current. Continuity of that surface is desirable with minimumY of interruption. Inasmuch, however, as part ofthe surface is connected. with the anode and another part with the cathode, and` anode and cathodehave to be at different D; C. potentials, a discontinuity meeting this circumstance follows of necessity. 'Ihe problem `therefore presentsitself of providing a structure of resonator which has a' discontinuity edefctivetolmaintain difference of'D. C.' potential without materially interfering with the continuity for high frequency current flow.

The present invention accordingly has for its general object the provision" of' improved, ef-

remain the same;-

Of` analogous nature isi another object which thel invention seeks to accomplish, namely,Y that capa'citative variationrnay be accomplished without disturbing the relation Ofthe@ emission effect between the diode electrodes:

Another object of the' invention is to obtain mechanical rigidity of anelectrode notwithstand= ing Inova-bility thereof for tuning purposes.

A further object ofthe" invention isl to permit substantially unirripaired H. FL. current" flowk on the interior or cavity wall whilemaintainig a discontinuity'in the wall for other purposes Y Still further objects of the invention will appear as the? description progresses, both by di- Y rect? recitation thereof and by; implication from the context.

Referring to the accompanying drawing in which like numerals,` of reference indicate similar parts throughout the several' views;

Figure 1 is a vertical sectionalview of anultia high frequency device constituted as adiode de'- tector. i

Figure-"2 across-Section on line II-TI of Fig; I. y

Figure 3'i`s` an enlargement ofithatpartof Fig. 1 showing the structural' assembly bywhich' effectivediscontinuity i's obtained as* to D; C. potentialfbu't with theV effect of electricalic'ontinuity iii regards to the H. E. current; and

Figure' 4 is a viewv siniila'rto' Fig.' 3 showing a modified construction. 1

In thespeciiic embodiment of the invention illustrated in said'V drawing, thereference'fnn'iexal lildesiglnates a sealed envelope, shownas of glass, with a reentrant glass stem Il therein' from which projects a metallic; collar I2 flared at itsupper'end to provide a' harige I3 in a plane transverse to the' saidv collar. Above the collar and flange isa tubular cathode I44 the upper end of which isclosed, as by integral end `I'5,.and the lower end. of' which has a. Wide ange I6 priojecting radially considerably" beyond. the fiang'e |3 of' the` saidv collar- 122` The cathode, flange` B otherwise.

rests fiatwise on the collar fiange I3, coaxial therewith and secured thereto as by Welding or Within the cathode I4 is a suitable heater II here illustrated as av coiled filament attached to appropriate lead-in wires I8 sealed through stem III.,

Coaxial with the cathode I4 is an anode I9' the lower part of which is hollow to provide a skirt portion 2l)` which girdles the upper end portion of the cathode in desired closely spaced relation thereto for obtaining the desired short transit time of electron path from cathode to anode. The cathode is indicated as having an emissive oxide coating 2| on the cylindrical portion thereof engirdled by the anode. 4Particular attention is called to the fact that emissionrfrom the cathode ls preferably restricted to the region therefrom by mica or other dielectric 33. While the headers have peripheral cylindrical portions 3| for welding or otherwise securing the same to the outer wall 23 of the resonant chamber, the part of primary importance is the Vplate or Washer-like body portion 32 of the inner header over- H. F. current across the area of D. C. disconincluded between the cylindrical walls of the` cathode and skirt portion of the anode.

The region within which cathode I4 and skirt portion of anode I9` are located, is constructed as a resonant chamber 22 the walls of which are metal. The specinc construction involved provides a cylindrical outer sidewall 23, preferably of copper, coaxial with the cathode and anode and having its lower margin feather-edged and sealed to the glass portion 0f the envelopeand thereby constituting a part of the said envelope.

The upper vpart of said side wall 23 is provided with an inner shoulder 24 for properly locating and supporting the rim or edge of a transverse flexible metallic diaphragm 25. The body portion of anode I'S'projects through the middle of said diaphragm, and said diaphragm is vacuum sealed both to the anodeand to said outer wall. By virtue o1" the resilient flexibility of the diaphragm, the length of the chamber may be varied as well as a changecbeing obtained in capacity between anode and cathode, and thereby permits desired tuning of the same. k

Both for tuning purposes and for accurate rigid mounting of the anode, the upper end of the anode is shown of sturdy construction and carried by an equally sturdy capV ZS'in turn supported atits outer margin from the side wall 23 of the resonator chamber. The structure illustrated includes a ring 2'I brazed or otherwise secured onthe exterior of said wall 23 next the 32 is made radially a quarter wave length in dielectric 30 referredV to the generated wave of oscillations in the resonant chamber. Wave length in dielectric 30 is shorter than in airor vacuum of the chamber. The construction accordingly sets up ahigh impedancewat the outer periphery of flange I6 which reects a low impedance at the inner `peripheral edge of plate 32 thereby presenting the eifect of electrical continuityV across the gap between flange and plate at the inner periphery of the said plate.

For more denitely assuring the condition of high impedance at the periphery of the flange, a vconstruction such as shown in Figure/1 may be employedx In this instance the headers are constructed as before, but spaced apart somewhat Vfarther to accommodate a different flange conas before, a quarter wave length measured in the upper edge thereof and threaded on its outer surface tointer-engage with threads 28 on'the inside of a .skirtV portion of said cap 26. Similarly theupper end of anode I9 provides ay stern dielectric 35a intervening between the overlapping portions. At the underside kof the ,ilange is an impedance section comprised ofan open annular cavity 30h between the under side of `a part of said iange vand a parallel plate 3Go the inner periphery of which is bent upwardly and secured,V

by welding or otherwise to said flange, the. upwardly bent portion 35d forming an innerend wall for the annular cavity 30h.v The outer periphery of the parallel plate 33e turns upward beyond the end of ange Iiia, as at 33e with a gap 39j between the said up-turned Vend 30e and end Vofiiange IEa. Part of dielectric 30a closes the end of gap 30j and thel parts are proportioned to establish substantially a free space quarter wave length distance from the said closed Y end 39d to the dielectric'closure ofY gap 3f. yThe .i low impedance at closed end Bildrwill, accordingly considerable rotation of the cap is required for a.v small longitudinal movement of the anode,

thereby obtaining va fine tuning adjustment.

and the Vresonator side wall. The structure shown consists in providing a pair ofheaders, one above and theother below said flange and separated reilect a high impedance at gap 30j, as desired, and accordingly insures a high impedance at the periphery of lflange Ilia toY insure, in turn, a low impedance at the inner periphery of plate 32. It may be further added that the dielectric, k'such as mica, fills the region beyond upturned end or rim 30e and the wall 23 of-the resonant chamber, as well as the space between thelower header and the cavity-forming under plate 33o. A few holes or slots 3tlg may be provided from the evacuated chamber into annular cavity 30h for enabling that cavity likewise to be evacuated.

In practice, the device' is evacuated through the stem, as by tubulationopening 33 therein,

therebeing suitable slots 34 in the collar I2 and slots 35 in ange I 6 or I 6a to accomplish'complete cutgassing so that resonant chamber 22 will function in vacuum. oscillations set up in said chamber may be transferred for useful purpose by a usualoutputmeans, suchas concentric line and loop 36 shown.

It may now be particularly pointed out that by proper choice of dimensions of the several parts, the spacing of cathode and anode can be very small, limited only by mechanical considerations, thus making possible a time of transit in this diode consistent with satisfactory operation at ultra high frequencies. The change in the lump-ed capacity of the device due to movement of the anode it with diaphragm 25, with corresponding change of frequency for tuning purposes, does not afiect the transit time of electrons between cathode and anode. Likewise the dielectric spacing of flange and plates with impedance control between the cathode and outer wall provides an eiiicient means for obtaining a high frequency rectified current or beat frequency.

While arbitrarily selected eXemplifications of the invention have been herein shown, it is to be understood that this has been done through necessity of presenting a physical embodiment of the invention and it therefore follows that all matter contained in the specification or depicted in the drawing shall be interpreted as illustrative and not necessarily in a limiting sense, and as setting forth the true` scope of invention by statements of both the generic and specic features thereof which as a matter of language enceinpass the inventive concept.

We claim:

1. An ultra high frequency device comprising electrodes of which one is a cylindrical cathode and another is an anode having a cylindrical skirt portion telescopically overlapping an end of the cathode, said cathode having an emissive portion and a non-emissive capacitative portion in continuation of the emissive portion and the emissive portion being at the said end overlapped by the cylindrical skirt portion of the anode,`

said skirt portion being radially opposite the entire emissive portion of the cathode, and the non-emissive portion of the cathode projecting from said skirt, an enclosure around said electrodes, and movable means extending from said enclosure to one of said electrodes for adjusting the telescopic overlap of said electrodes longitudinally and thereby varying the inter-electrode capacity while maintaining constant electronpath spacing between said electrodes.

2. An ultra high frequency device comprising a diode structure having a cathode and anode and evacuated enclosure therefor, said cathode and anode overlapping and having a constant radial spacing for the eiectron path therebetween and telescopically adjustable as to distance of overlap for varying inter-electrode capacity thereat, and means other than said spacing establishing direct current discontinuity in the enclosure between the cathode and anode comprising parts insulated from each other and overlapping an odd quarter wave-length distance and establishing thereat an effect of negligible impedance to high frequency current and establishing eifect of electrical continuity t0 high frequency current.

3. An ultra high frequency device comprising a metallic enclosure forming a resonator, a cathode and an anode each within said resonator, and an impedance section within said enclosure comprising parts insulated from each other and overlapping an odd quarter wave-length distance, said cathode being connected with one of said overlapping parts of the impedance section and said anode being connected with another of said overlapping parts of the impedance section, whereby said impedance section establishes a direct currentA discontinuity between the cathode and anode and establishes thereat an eect of negligible impedance to high frequency current and establishes effect of electrical continuity for high frequency current.

4. An ultra high frequency device comprising a metallic enclosure forming a resonator, a cathode and an anode in said resonator, said cathode having a iange projecting laterally therefrom and said enclosure having a plate overlapping said fiange a distance substantially equal to a quarter wave-length in dielectric, and dielectric between said overlapping plate and flange.

DAVID GORDON CLIFFORD.

ILIA E. MOUROMTSEFF.

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